These synthetic 3D benchmarks from Futuremark allow you to evaluate the expected performance of a system with different generations of games. As each 3DMark uses different features and quality settings, it allows you to get an idea of how your system will perform. 3DMark01
3DMark01 has become more and more a system benchmark rather than a graphics card benchmark over the years. Nowadays, you can really see the difference in DDR2 and DDR3 memory setups, high and low FSB setups and so on.
Due to 3DMark01 being cpu dependant, both cards perform pretty much the same.3DMark03
3DMark03 is very GPU dependant, which comes down to: the more cores, the higher the score. SLI and CF performance increase is spectacular in this benchmark.
Non-overclocked, the HD4850 is noticeably slower than the 9800GTX, but with a little bit of overclocking you can outperform the Nvidia competitor quite easily.3DMark05
This product of the 3DMark series is again more CPU dependant than its predecessor, meaning that an overclocked CPU will have a big influence on the end score.
Nvidia's 9800GTX is ruling in this one, even overclocking doesn't really help.3DMark06
3DMark06 is known to stress the GPU to the maximum and provides SM2.0 and SM3.0 test to compare products.
In Futuremark's latest XP 3D benchmark, the 4850 is capable of beating it's direct competitor when overclocked, be it with a small margin.Aquamark3
While this 3D benchmark is aging quickly, it still serves as a good evaluation tool for system performance, as it stresses the VGA, CPU and memory subsystem, any advantage had from a faster motherboard or memory setting will be apparent.
Small differences in the AM3 benchmark, the HD4850 is trailing the 9800GTX.